Function 'subsindex' is not defined for values of class 'tf'

I have been trying to work on GSO code, and it keeps showing this error I made sure there was no variable in any function called step.

Does anyone point me towards what might be wrong?

Function 'subsindex' is not defined for values of class 'tf'.

Error in UpdateLuciferin (line 28)
J(i,:)=k(2);

Error in GSO (line 34)
UpdateLuciferin; % Update the luciferin levels at glowworms’

      function UpdateLuciferin
  global n A J Ell gamma ro
  for i = 1 : n
  T = A(i,1);
  K = A(i,2);
  G=[0 0 0 1 0 0 0 0 0;0 0 0 0 1 0 0 0 0;0 0 0 0 0 1 0 0 0;-0.003184 0 0 0 0 -0.0199 0 0 0.0199;0 0.0002985 0 0 0 0 0 0 0;0 0 -0.000398 0.00997 0 0 -0.00997 0 0;0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0];
  B=[0 0 0;0 0 0;0 0 0;-1 0 0;0 -0.25 0;0 0 -0.5;1 0 0;0 1 0;0 0 1];
  C=[1 0 0 0 0 0 0 0 0;0 1 0 0 0 0 0 0 0;0 0 1 0 0 0 0 0 0];
  D=0;
  sys = ss(G,B,C,D);
  i=tf(sys);
  X=i(1,1);
  Y=i(1,2);
  Z=i(1,3);
  num=[(0.6*(T^2)*K) 4.8*K*T 9.6*K];
  den=[8*T 0];
  tfPID=tf(num,den);
  xtf=X*tfPID;
  ytf=Y*tfPID;
  ztf=Z*tfPID;
  a=xtf/(1+xtf);
  b=ytf/(1+ytf);
  c=ztf/(1+ztf);
  ftf=a+b+c;
  y=step(ftf);
  yinfo=stepinfo(y)
  k=struct2cell(yinfo);
  J(i,:)=k(2);
  % The Matlab ’Peaks’ function is used here. Please replace it with
  % the multimodal function for which peaks are sought
  %J(i,:) =-(647.9-0.7276.*x+0.6765.*y-0.1455.*x.^2+0.2327.*x.*y-0.17.*y.^2+0.001928.*x.^3-0.003643.*x.^2.*y+0.00255.*x.*y.^2-0.0008596 .*y.^3+0.0001613.*x.^4-0.0002075.*x.^3.*y+(1.244e-05).*x.^2.*y.^2+(9.413e-06).*x.*y.^3+0.0001003.*y.^4);
      Ell(i,:) = (1-ro)*Ell(i,:) + gamma*J(i,:);
  end

Answer 1

[Walter Roberson]

i=tf(sys);

So i is a transfer function

J(i,:)=k(2);

That you are trying to use to index an array.

[Pulkit Sharma]

So, it is because I am using "i" twice? I rectified this, changed it to

    j=tf(sys)

the other i remains the same. Now I have Conversion to double from cell is not possible.

function UpdateLuciferin
global n A J Ell gamma ro
for i = 1 : n
T = A(i,1);
K = A(i,2);
G=[0 0 0 1 0 0 0 0 0;0 0 0 0 1 0 0 0 0;0 0 0 0 0 1 0 0 0;-0.003184 0 0 0 0 -0.0199 0 0 0.0199;0 0.0002985 0 0 0 0 0 0 0;0 0 -0.000398 0.00997 0 0 -0.00997 0 0;0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0];
B=[0 0 0;0 0 0;0 0 0;-1 0 0;0 -0.25 0;0 0 -0.5;1 0 0;0 1 0;0 0 1];
C=[1 0 0 0 0 0 0 0 0;0 1 0 0 0 0 0 0 0;0 0 1 0 0 0 0 0 0];
D=0;
sys = ss(G,B,C,D);
j=tf(sys);
X=j(1,1);
Y=j(1,2);
Z=j(1,3);
num=[(0.6*(T^2)*K) 4.8*K*T 9.6*K];
den=[8*T 0];
tfPID=tf(num,den);
xtf=X*tfPID;
ytf=Y*tfPID;
ztf=Z*tfPID;
a=xtf/(1+xtf);
b=ytf/(1+ytf);
c=ztf/(1+ztf);
ftf=a+b+c;
y=step(ftf);
yinfo=stepinfo(y)
k=struct2cell(yinfo);
J(i,:)=k(2);
% The Matlab ’Peaks’ function is used here. Please replace it with
% the multimodal function for which peaks are sought
%J(i,:) =-(647.9-0.7276.*x+0.6765.*y-0.1455.*x.^2+0.2327.*x.*y-0.17.*y.^2+0.001928.*x.^3-0.003643.*x.^2.*y+0.00255.*x.*y.^2-0.0008596 .*y.^3+0.0001613.*x.^4-0.0002075.*x.^3.*y+(1.244e-05).*x.^2.*y.^2+(9.413e-06).*x.*y.^3+0.0001003.*y.^4);
Ell(i,:) = (1-ro)*Ell(i,:) + gamma*J(i,:);
end
end

[Walter Roberson]

global n A J Ell gamma ro

imports J, but we do not know it was initialized. If it was never explicitly initialized in another routine then it will become initialized to [] when it is imported as a global

k=struct2cell(yinfo);

makes k into a cell.

J(i,:)=k(2);

indexes the cell, producing a scalar cell, and tries to store that scalar cell within J. If J is not data type cell (perhaps because it is []) then that will fail.

[Pulkit Sharma]

Can k be converted to that type of data?

Edit- solved

function UpdateLuciferin
global n A J Ell gamma ro
for i = 1 : n
T = A(i,1);
K = A(i,2);
G=[0 0 0 1 0 0 0 0 0;0 0 0 0 1 0 0 0 0;0 0 0 0 0 1 0 0 0;-0.003184 0 0 0 0 -0.0199 0 0 0.0199;0 0.0002985 0 0 0 0 0 0 0;0 0 -0.000398 0.00997 0 0 -0.00997 0 0;0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0;0 0 0 0 0 0 0 0 0];
B=[0 0 0;0 0 0;0 0 0;-1 0 0;0 -0.25 0;0 0 -0.5;1 0 0;0 1 0;0 0 1];
C=[1 0 0 0 0 0 0 0 0;0 1 0 0 0 0 0 0 0;0 0 1 0 0 0 0 0 0];
D=0;
sys = ss(G,B,C,D);
l=tf(sys);
X=l(1,1);
Y=l(1,2);
Z=l(1,3);
num=[(0.6*(T^2)*K) 4.8*K*T 9.6*K];
den=[8*T 0];
tfPID=tf(num,den);
xtf=X*tfPID;
ytf=Y*tfPID;
ztf=Z*tfPID;
a=xtf/(1+xtf);
b=ytf/(1+ytf);
c=ztf/(1+ztf);
ftf=a+b+c;
y=step(ftf);
yinfo=stepinfo(y);
k=struct2cell(yinfo);
v=cell2mat(k);
J(i,:)=v(2)
% The Matlab ’Peaks’ function is used here. Please replace it with
% the multimodal function for which peaks are sought
%J(i,:) =-(647.9-0.7276.*x+0.6765.*y-0.1455.*x.^2+0.2327.*x.*y-0.17.*y.^2+0.001928.*x.^3-0.003643.*x.^2.*y+0.00255.*x.*y.^2-0.0008596 .*y.^3+0.0001613.*x.^4-0.0002075.*x.^3.*y+(1.244e-05).*x.^2.*y.^2+(9.413e-06).*x.*y.^3+0.0001003.*y.^4);
 Ell(i,:) = (1-ro)*Ell(i,:) + gamma*J(i,:);
end
end

[Walter Roberson]

Not unless J just happens to be a global variable that refers to a table() object which seems unlikely.

I think it is much more likely that you failed to initialize the global variable J to be a cell array before you called the function.

[Pulkit Sharma]

I converted the cell to a matrix to solve the problem.